Antigenic determinants expressed on the bacterial cell surface are of importance in the serological characterization and microbiological diagnosis.The bacterial strains carrying these identical or similar antigenic epitopes might react with antibodies produced against other strains.In this study,strong immunogenicity and antigenic cross reactivity were demonstrated among V.choleae O1,S.flexnerii 2a and H.influenzae b surface components.The enzyme linked immunosorbent assay (ELISA) results were supported by West blot analysis,where at least 20 antigenic bands,were obtained in each of the reactions,when the surface components were reacted with the homologous antisera.The indirect ELISA results also demonstrated high degree of antigenic relatedness between the surface components of these species,where each surface component was reacted with the heterologous antisera. West blot analysis also revealed cross reactions between the surface components suggesting common distribution of antigensepitopes in these bacteriaI species.This study,thus,gave a clear idea of the level of antigenic sharing and variations among the pathogenic V.cholerae O1,S.flexneri 2a and H.influenzae b strains, which in future,may help in selecting a proper candidate for vaccines and immunodiagnostics development.